The family of missing retired FBI agent Robert Levinson is accusing the U.S. government of abandoning him.

According to the State Department, Levinson disappeared in March 2007 during a business trip in Iran. But a recent investigation by the Associated Press revealed Levinson was working on a secret CIA assignment.

Although the Iranian government denies any involvement in his disappearance, the United States is certain Iran can help find him.

"I can't tell you what happened or how the sequence was, but I think the Iranian government has the ability to help us here. And we hope they will," Secretary of State John Kerry said.

Despite the lack of proof he's still alive, the United States insists it has not abandoned Levinson. But some lawmakers are saying the CIA did not tell Congress the truth about the missing agent.